package com.heatup.apt.common.util;

/**
 * Created by b3st9u on 16/9/7.
 */
public class DistanceUtil {



    private static final double EARTH_RADIUS = 6378137;
    private static double rad(double d)
    {
        return d * Math.PI / 180.0;
    }

    /**
     * 根据两点间经纬度坐标（double值）
     * @param lng1
     * @param lat1
     * @param lng2
     * @param lat2
     * @return 两点间距离，单位为米
     */
    public static double GetDistance(double lng1, double lat1, double lng2, double lat2)
    {
        double radLat1 = rad(lat1);
        double radLat2 = rad(lat2);
        double a = radLat1 - radLat2;
        double b = rad(lng1) - rad(lng2);
        double s = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin(a/2),2) +
                Math.cos(radLat1)*Math.cos(radLat2)*Math.pow(Math.sin(b/2),2)));
        s = s * EARTH_RADIUS;
        s = Math.round(s * 10000) /(double)10000;
        return s;
    }



    /**
     * 算地球上任意两点(经纬度)距离
     *
     * @param long1 第一点经度
     * @param lat1  第一点纬度
     * @param long2 第二点经度
     * @param lat2  第二点纬度
     * @return 返回距离 单位：千米
     */
    public static double distance(double long1, double lat1, double long2,
                                  double lat2) {
        double a, b, R;
        R = 6378137; // 地球半径
        lat1 = lat1 * Math.PI / 180.0;
        lat2 = lat2 * Math.PI / 180.0;
        a = lat1 - lat2;
        b = (long1 - long2) * Math.PI / 180.0;
        double d;
        double sa2, sb2;
        sa2 = Math.sin(a / 2.0);
        sb2 = Math.sin(b / 2.0);
        d = 2
                * R
                * Math.asin(Math.sqrt(sa2 * sa2 + Math.cos(lat1)
                * Math.cos(lat2) * sb2 * sb2));
        return d / 1000;
    }

    public static void main(String[]args){
        System.out.println(distance(111.11, 222.222, 333.333, 222.12));
        System.out.println(GetDistance(113.950099,22.555188,116.388746,39.935297));
    }


}
